Cam-driven pump mechanism for a battery-powered grease gun

ABSTRACT

A cam-driven pump mechanism for a battery-powered grease gun includes a cam driver and a cam-driven pump. The grease gun has a transition body having a grease channel and a casing having an inner chamber. The cam driver is mounted in the inner chamber. The cam-driven pump has a cylindrical cam, a sliding block, a follower and a piston. The cylindrical cam is rotatably mounted in the inner chamber, is rotated by the cam driver and has an eccentric annular groove. The sliding block is slidably mounted in the casing. The follower is securely attached to the sliding block and mounted slidably in the eccentric annular groove. The piston is mounted slidably in the grease channel and connects to the sliding block. Consequently, use of the cylindrical cam prevents localized friction on the sliding block and keeps the pump mechanism from wearing excessively.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a battery-powered grease gun, and more particularly to a battery-powered grease gun that uses a cylindrical cam to drive a pump mechanism to continuously discharge grease from the grease gun.

2. Description of Related Art

With reference to FIGS. 5 and 6, a conventional battery-powered grease gun has a body (60) and a pump assembly (not numbered). The pump assembly is mounted in the body (60) and comprises a motor (64), a planetary gear assembly (65), a drive disk (66), a drive pin (67), a sliding block (68), a piston (69) and a transition body (61) with a drive channel (not numbered).

The body (60) has a grease channel (601), connects to a cylindrical lubricant cartridge holder (602) and comprises a ball check valve (62) and a discharge spout (63). The discharge spout (63) communicates with the grease channel (601). The ball check valve (62) is mounted between the grease channel (601) and the discharge spout (63) to control flow rates of grease in the grease channel (601) entering into the discharge spout (63).

The transition body (61) is attached to the body (60) with the drive channel communicating with the grease channel (601). The sliding block (68) is mounted slidably in the drive channel and has a transverse slot (681) and an attachment slot (682). The planetary gear assembly (65) reduces the speed and increases the torque of the motor (64). The drive disk (66) is coupled to and rotated by the planetary gear assembly (65) and has an eccentric threaded hole (not numbered). The drive pin (67) has a threaded end (not numbered) and a bottom end (not numbered). The threaded end is screwed into the eccentric threaded hole in the drive disk (66), and the bottom end extends into the transverse slot (681) in the sliding block (68) to drive the sliding block (68) back and forth in the drive channel. The piston (69) has a distal end (not numbered) and a proximal end (not numbered). The distal end is mounted slidably in the grease channel (601), and the proximal end is attached to the attachment slot (682) in the sliding block (68). The cylindrical lubricant cartridge holder (602) is attached to the body (60) and communicates with the grease channel (601) to supply lubricant to the grease channel (601).

To discharge the grease, the motor (64) rotates the drive disk (66) through the planetary gear assembly (65). The rotating drive disk (66) and drive pin (67) move the sliding block (68) back and forth in the drive channel. The sliding block (68) moves the piston (69) back and forth, which pumps the grease in the grease channel (601) out through the discharge spout (63).

Since a single drive pin (67) drives the sliding block (68) as the driving pin (67) slides in the transverse slot (681), the drive pin (67) presses against half of each face of the transverse slot (681) when pushing the sliding block (68) in one direction. This action causes the transverse slot (681), the sliding block (68) and the drive channel to wear unevenly. This uneven wear eventually causes the pump mechanism to operate erratically and be unreliable. Furthermore, the uneven wear makes replacement of the sliding block (68) periodically necessary.

To overcome the shortcomings, the present invention provides a cam-driven pump mechanism to mitigate or obviate the aforementioned problems.

SUMMARY OF THE INVENTION

The main objective of the present invention is to provide a cam-driven pump mechanism for a battery-powered grease gun, and the cam-driven pump mechanism keeps any part of the pump mechanism from wearing excessively to extend the life of the grease gun.

The cam-driven pump mechanism for a battery-powered grease gun in accordance with the present invention includes a cam driver and a cam-driven pump. The grease gun has a body with a discharge assembly, a casing and a cartridge holder. The casing has an inner chamber and, the discharge assembly has grease channel communicating with the inner chamber.

The cam driver comprises a planetary gear assembly and a motor mounted in the inner chamber.

The cam-driven pump comprises a cylindrical cam, a sliding block, a follower and a piston. The cylindrical cam is mounted rotatably in the inner chamber, is connected to and driven by the cam driver and has an eccentric annular groove. The sliding block is mounted slidably in the inner chamber and is aligned with the grease channel. The follower is attached securely to the sliding block and mounted slidably in the eccentric groove in the cylindrical cam, which causes the sliding block to reciprocate when the cylindrical cam rotates. The piston is slidably mounted in the grease channel and connected to the sliding block to slide reciprocally in the grease channel to pump grease continuously out of the grease gun.

Consequently, use of the cylindrical cam prevents localized friction on the sliding block and keeps the parts of the pump mechanism from wearing excessively.

Other objectives, advantages and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a battery-powered grease gun in accordance with the present invention;

FIG. 2 is an exploded perspective view of the battery-powered grease gun in FIG. 1;

FIG. 3 is an exploded perspective view of a cam-driven pump in the grease gun in FIG. 1;

FIG. 4 is an enlarged operational cross sectional plan view of the cam-driven pump mechanism in FIG. 3;

FIG. 5 is an enlarged operational cross sectional plan view of a conventional grease gun pump mechanism in accordance with prior art; and

FIG. 6 is an enlarged perspective view of a conventional sliding block of the conventional pump mechanism in FIG. 5.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

With reference to FIGS. 1 and 2, a cam-driven pump mechanism in accordance with present invention is used in a battery-powered grease gun (not numbered). The battery-powered grease gun has a body (10), a cartridge holder (50) and a cam-driven pump mechanism. The body (10) comprises a casing (12) and a discharge assembly (not numbered).

With further reference to FIG. 4, the casing (12) comprises two half shells (not numbered) and has a top (not numbered) and an inner chamber (121) formed when the half shells connect to each other.

The discharge assembly is mounted on the top of the casing (12) and comprises a transition body (11), a ball check valve (14) and a discharge adapter (15). The transition body (11) has a top (not numbered), a bottom (not numbered), an inward side (not numbered), an outward side (not numbered), a grease channel (110), a ball check valve housing (116) and a cartridge connector (117).

The grease channel (110) is formed longitudinally through the transition body (11) and has a top opening (111), a bottom opening (112) and a supply port (114).

The cartridge connector (117) is formed on the inward side of the transition body (11) around the supply port (114) to hold the cartridge holder (50). The supply port (114) is defined on the inward side of the transition body (11) inside the cartridge connector (117) and communicates with the grease channel (110).

The ball check valve housing (116) is formed at the top of the transition body (11) and is aligned with the top opening (111). The ball check valve (14) is mounted in the ball check valve housing (116) to keep grease from flowing back into the grease channel (110) from the top opening (111).

The cartridge holder (50) is mounted on the top of the casing (12), is connected to the cartridge holder connector (117) of the transition body (11) and holds a lubricant cartridge (not shown).

With further reference to FIG. 3, the cam-driven pump mechanism comprises a cam driver (21) and a cam-driven pump (40). The cam driver (21) is mounted in the inner chamber (121) and includes a planetary gear assembly (30) and a motor (20). The planetary gear assembly (30) comprises a set of planetary gears (not numbered) and a gear housing (31). The gear housing (31) is mounted in the casing (12) and has a top (not numbered), a bottom (not numbered) and a lower inner chamber (311). The planetary gears are mounted in the lower inner chamber (311).

The motor (20) is mounted in the casing (12) and is aligned coaxially with and connects to bottom of the planetary gear assembly (30) so that the set of planetary gears will reduce the output speed and increase the output torque of the motor (20).

The cam-driven pump (40) comprises a cylindrical cam (41), a follower (42), a sliding block (43), a piston (44) and a bushing (45).

The cylindrical cam (41) is mounted rotatably between the transition body (11) and the gear housing (31), is connected to, aligned with and driven by the planetary gears and has an outside surface (not numbered), a bottom end (not numbered), an eccentric annular groove (411) and a drive shaft (412). The eccentric annular groove (411) is formed in the outside surface. The drive shaft (412) is rectangular, is formed on the bottom end and connects to the planetary gears so the motor (20) will rotate the cylindrical cam (41) through the planetary gear assembly (30).

The sliding block (43) is mounted slidably in the inner chamber (121) and has a front (not numbered), a top (not numbered), a follower hole (431) and a piston slot (432). The follower hole (431) is formed in the front of the sliding block (43). The piston slot (432) is formed in the top of the sliding block (43) and is aligned with the grease channel (110) in the transition body (11).

The follower (42) is a rod and has a distal end (421) and a proximal end (422). The proximal end (422) is mounted securely in the follower hole (431) in the sliding block (43). The bushing (45) is mounted around the follower (42), and the distal end (421) of the follower (42) and the bushing (45) are mounted slidably in the eccentric annular groove (411). When the cylindrical cam (41) rotates, the follower (42) is driven alternately up and down by the eccentric annular slot (411).

The piston (44) has a distal end (not numbered), a proximal end (not numbered) and an annular groove (441). The annular groove (441) is formed around the piston (44) near the proximal end and is engaged with the piston slot in the sliding block (43). The distal end is mounted slidably in the grease channel (110), moves reciprocally in the grease channel (110) and pumps grease out of the grease channel (110) through the discharge adapter (15).

Consequently, use of the cylindrical cam (41) avoids localized friction and uneven wear on the sliding block (43). Furthermore, the bushing (45) mounted around the follower (42) and in the eccentric annular groove (411) keeps the follower (42) and the eccentric annular groove (411) from wearing excessively. The bushing (45) is inexpensive and can be easily replaced to restore the cam-driven pump (40) to a virtually new condition. The cam-driven pump mechanism in accordance with the present invention is durable and operates more efficiently and smoothly than the conventional pump mechanism. The durable pump mechanism extends the life of the grease gun.

Even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the scope of the appended claims. 

1. A cam-driven pump mechanism for a battery-powered grease gun having a body with a casing with an inner chamber and a discharge assembly with a transition body having a grease channel aligned and communicating with the inner chamber, and the cam-driven pump mechanism comprising: a cam driver adapted to be mounted in the inner chamber; and a cam-driven pump driven by the cam driver and the cam-driven pump comprising a cylindrical cam adapted to be rotatably mounted in the inner chamber, rotated by the cam driver and having an outside surface and an eccentric annular groove formed in the outside surface; a follower mounted slidably in and driven by the eccentric annular groove in the cylindrical cam; a sliding block adapted to be mounted slidably in the inner chamber, attached securely to the follower and driven by the follower; and a piston attached to the sliding block, adapted to be mounted slidably in the grease channel and driven up and down in the grease channel by the sliding block.
 2. The cam-driven pump mechanism as claimed in claim 1, wherein the cam driver comprises a planetary gear assembly comprises a gear housing adapted to be mounted in the casing; and a set of planetary gears mounted in the gear housing and connected to the cylindrical cam; and a motor attached to the gear housing and connected to and rotating the set of planetary gears to rotate the cylindrical cam.
 3. The cam-driven pump mechanism as claimed in claim 2, wherein the cylindrical cam further has a rectangular drive shaft connected to the set of planetary gears; the sliding block has a follower hole in which the follower is securely attached and a piston slot; and the piston has an annular groove engaging with the piston slot.
 4. The cam-driven pump mechanism as claimed in claim 3, further comprising a bushing mounted around the follower and mounted slidably in the eccentric annular groove in the cylindrical cam. 